Authorities are questioning the cause of death of a South Korean man who was initially thought to have been killed in a cell phone battery explosion, according to news reports.

The unidentified 33-year-old man had been found dead next to an electric shovel at the quarry where he worked, and a mobile handset with a melted battery was discovered in his shirt pocket. His injuries reportedly included a punctured heart, ruptured lungs, and broken ribs and spine.

But the National Institute of Scientific Investigation determined that those injuries were too severe to be attributed to a phone battery explosion, according to the Associated Press, citing reports from the Yonhap news agency. Final results from an autopsy are expected in about 15 days.

LG, which makes the phone model in question, reportedly said an explosion as originally described was virtually impossible.